The present invention relates to a sound image orientation apparatus having a cross-talk cancel and correcting function and forming a sound field on the basis thereon.
Usually, a spatial propagation from a virtual sound source to the ear of a listener is modeled to add such an acoustic effect to which the virtual sound source is oriented (for instance, see Patent Documents 1 to 3).
A sound image orientation apparatus having a cross-talk cancel function has been hitherto disclosed (for instance, see, Patent Document 1.). A component reaching from a right speaker to the left ear or vice versa is referred to as a cross-talk and a function for canceling the cross-talk is referred to as a cross-talk cancel. The cross-talk cancel means a technique that enables the left side ear to hear only the sound of a left side speaker and the right side ear to hear only the sound of the right side speaker and eliminates the orientation of the speakers themselves. In this technique, the spatial propagation from the sound source to the ear of the listener is modeled and such a sound wave as to cancel the cross-talk at the spot of the ear of the listener is processed to a digital sound source to be sounded in accordance with a calculation by an inverse matrix. Then, for instance, when a front floor type speaker is used and a rear model head transfer function is used to orient a sound image from a rear side or to form a free sound field, the cross-talk cancel is necessary for exhibiting its effect.
In the Patent Document 1, a stereo acoustic device or the like is disclosed in which the cross-talk cancel is carried out or the sound field is formed by employing a result obtained by previously measuring the model head transfer function measured by using a dummy head.
However, when the cross-talk cancel is carried out or a rear orientation is added by using the model head transfer function, its effective range can be effected only in view of a pin-point or it is disadvantageously affected by a personal difference. Thus, devices of Patent Documents 2 and 3 are disclosed.
In the Patent Document 2, a sound image orientation control method is disclosed in which, since the model head transfer function for a high frequency reproduces peaks or dips in view of frequency characteristics different from those of a listener, when a sound image orientation is realized, unnecessary peaks or dips in view of frequency characteristics are removed for reasons of the generation of an unnatural tone quality.
Further, the patent Document 3 discloses a sound image orientation apparatus mainly using a headphone in which peaks or dips are formed in a predetermined frequency to reproduce a head transfer function. Further, in the Patent Document 3, there is a description that since the central frequency of the peaks or the dips or the optimum value of a half-value width is different respectively to listeners, the central frequency or the half-value width is adjusted so that each listener can most feel a sense of front and rear.
[Patent Document 1] JP-A-2001-86599
[Patent Document 2] JP-A-6-178398
[Patent Document 3] JP-A-2003-153398
However, as in the Patent Document 2, when the peaks or the dips of the high frequency are removed as unnecessary parts, a problem arises that a sound image effect is actually insufficient. On the other hand, when the peaks and the dips are left as they are, a problem arises that a tone quality is unnatural and sound may be sometimes hardly heard due to a personal difference or a deviation from a position supposed to be effected by a model head transfer function.
Further, as described above, in the Patent Document 3, though there is a description that the central frequency or the half-value width is adjusted so that each listener can most feel the sense of before and after. However, since the peaks and dips are added to a diffusing filter simulating a single ear spectrum, it may not be necessarily said that the device disclosed in the Patent Document 3 represents the head transfer function.